 Mon Jul 9 23:18:09 2012, yuta, Update, LSC, PRMI got more stable a bit 
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I modified filiters for LSC_MICH and LSC_PRCL.
Although modes we can see at POP and AS look still bad, error signals are less glitchy than I see before (elog #6886).
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 Tue Jul 10 03:16:17 2012, yuta, Update, LSC, PRMI got more stable a bit
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I modified filiters for LSC_MICH and LSC_PRCL again to cope with power recycling gain fluctuation.
After some more alignment, power recycling gain increased (but still ~3.7). It fluctuates more than a factor of 2, and I began to see glitches again.
So I needed more gain margin, as Koji pointed out. |
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Tue Jul 10 17:47:55 2012, yuta, Update, SUS, PRM oplevs fixed
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I centetered PRM oplev, lowered gain and PRM oplev servo is not oscillating any more.
It is OK for more than a softball practice.
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Tue Jul 10 21:37:05 2012, yuta, Update, LSC, PRMI glitch study
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PRMI glitch certainly comes from power recylcing gain fluctuation.
I confirmed this by
- Reading the value of POPDC at the time when there's glitch in error signals |
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Wed Jul 11 02:25:11 2012, yuta, Update, LSC, PRMI beam spot motion might be from PRM/BS motion
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My hypothesis from the measurements below, to explain PRMI beam spot motion is;
Stack motion at 3.3 Hz largely couples to BS and PRM angular motion. |
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Wed Jul 11 03:53:41 2012, yuta, Update, LSC, BS 3.3 Hz motion on MI
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It is not as dramatic as PRMI, but I could see BS 3.3 Hz motion at AS and REFL when MI is locked at dark fringe.
Below is uncalibrated spectra of REFLDC and ASDC when
Red: MI is locked at dark fringe |
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Wed Jul 11 13:36:58 2012, yuta, Update, SUS, OSEM and oplev spectra of optics
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Below is angular spectra of every suspended core optics.
As you can see, there's a peak at 3.3 Hz for BS and PRM angular motion. Compared with other optics, they look large.
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Wed Jul 11 16:19:08 2012, yuta, Update, SUS, oplev servo phiology
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I heard that Steve did great work on oplev in Feb 2012.
Here's summary what happened to oplev since then.
Someone changed oplev filters and gain. I couldn't find elog about it. Does anyone know? |
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Thu Jul 12 02:12:42 2012, yuta, Update, SUS, BS 3.3 Hz motion
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I tried to reduce BS 3.3 Hz motion with local damping. 3.3 Hz probably comes from the stack, but I want to reduce this because PRMI beam spot is moving
in this frequency.
I tried it by putting some resonant gains to oplev servo and OSEM damping servo, but failed. |
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Thu Jul 12 13:27:16 2012, yuta, Update, SUS, measured OLTFs of PRMI optics' SUSPOS
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I measured openloop transfer functions of PRM/BS/ITMX/ITMY SUSPOS servo.
They look great. They all have ~50 deg phase margin and damps only POS resonance.
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Thu Jul 12 23:15:34 2012, yuta, Update, LSC, PRMI LSC is making PRM motion worse
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It looks like PRMI LSC is making PRM motion (and BS motion) at ~3Hz worse.
I concluded this from measuring feedback signal of suspension servo and LSC servo.
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Fri Jul 13 15:49:38 2012, yuta, Bureaucracy, General, 40m Priority Action Items
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These are all priority action items need to be done before I come back (in mid-September).
BE PREPARED FOR THE FULL LOCK!
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Mon Feb 4 19:33:19 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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[Jenne, Yuta]
We redid PRM-PR2 cavity scan because last one (elog #7990) was taken with the sampling |
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Tue Feb 5 02:04:44 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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I redid PRM-PR2 cavity scan using oscilloscope to avoid anti-aliasing effect.
Measured Finesse was 104 +/- 1.
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Tue Feb 5 10:09:08 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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stdev of [0.764, 0.751] is 0.007, but what we need is the error of the averaged number. Statistical error of the averaged number is stdev/sqrt(n).
Quote:
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Tue Feb 5 19:32:47 2013, yuta, Summary, General, PR2/PR3 flipping and PRC stability
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We are considering of flipping PR2 and/or PR3 to make PRMI stable because PR2/PR3 seems to be convex.
I calculated dependency of the PRC stability on the PR2/PR3 curvature when PR2/PR3 flipped and not flipped.
Flipping looks OK, from the stability point of view. |
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Wed Feb 6 15:20:55 2013, yuta, Summary, General, FWHM was wrong
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I have to blame Jamie for putting extra 2 randomly.
Measured PRM-PR2 cavity finesse was actually 108 +/- 3 (even if you use digital system to get
data). |
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Thu Feb 7 10:35:35 2013, yuta, Update, General, Store optics in respective cabinets
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I'm not the one who opened the ITMX table yesterday, but thanks for reminding me.
I put POP DC oscilloscope and its cables back.
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Thu Feb 7 19:25:22 2013, yuta, Update, CDS, C1ALS filters reloaded
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Filters for C1ALS were all gone. So, I copied /opt/rtcds/caltech/c1/chans/C1GCV.txt and renamed it as C1ALS.txt.
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Fri Feb 8 12:39:32 2013, yuta, Update, Locking, PRMI work
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Half-PRC at this time already have two changes from the previous half-PRC; PR2 replaced/flipped and different TM before BS.
PRMI has only one change from the previous PRMI; PR2 replaced/flipped.
This is why I wanted to try PRMI first. But we now recognized that MI alignment (including REFL and AS alignment) is tough without using the arms, |
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Fri Feb 8 12:43:26 2013, yuta, Update, Computers, videocapture.py now supports movie capturing
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I updated /opt/rtcds/caltech/c1/scripts/general/videoscripts.py so that it supports movie
capturi |
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Fri Feb 8 19:29:44 2013, yuta, Summary, General, arbcav of half PRC with flipped PR2
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We need expected finesse and g-factor to compare with mode-scan measurement. Can you give us the g-factor of the half-PRC and what losses did you assumed
to calculate the finesse?
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Fri Feb 8 23:59:42 2013, yuta, Update, Locking, PR2-flipped half-PRC mode scan
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I did mode scan of PR2-flipped half-PRC to see if it behaves as we expect.
Measured finesse was 107 +/- 5 and g-factor is 0.98997 +/- 0.00006.
g-factor is 0.9800 +/- 0.0001. (Edited by YM; see elog |
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Sun Feb 10 17:30:39 2013, yuta, Update, Locking, PR2-flipped half-PRC mode scan
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I redid half-PRC mode scan by applying mislignment to PRM.
Half-PRC's sagittal g-factor is 0.9837 +/- 0.0006 and tangential g-factor is 0.9929 +/- 0.0005.
sagittal g-factor is 0.968 +/- 0.001 and tangential g-factor is 0.986 +/- 0.001. (Edited by YM; |
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Sun Feb 10 18:00:13 2013, yuta, Summary, LSC, PR2-flipped half-PRC spectra/OLTF
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To compare with future PRMI locking, I measured spectra of POPDC and feedback signal. I also measured openloop transfer function of half-PRC locking.
Beam spot motion was at ~ 2.4 Hz, not 3.3 Hz.
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Mon Feb 11 13:15:16 2013, yuta, Update, Locking, PR2-flipped half-PRC mode scan
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I found a mistake in my code (thanks Jamie!).
I forgot to square the g-factor.
I corrected the following elogs; |
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Mon Feb 11 21:03:15 2013, yuta, Update, Locking, PR2-flipped half-PRC mode scan
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To estimate the systematic effects to the g-factor measurement, I changed how to analyze the data in multiple ways.
From the estimation, I get the following g-factors for half-PRC;
tangential: 0.986 +/- 0.001(stat.) +/- 0.008(sys.) |
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Tue Feb 12 00:14:00 2013, yuta, Update, Locking, PRM coil balancing
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We tried to lock half-PRC tonight, but we couldn't. Why?? I could lock yesterday.
It locks for ~ 1 sec, but it beam spot motion freaks out mainly in yaw.
I tried to balance PRM coils, but oplev beam was clipped by MMT1...... |
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Tue Feb 12 00:50:08 2013, yuta, Update, Locking, PR2 oplev spectra
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I wanted to see if PR2 motion makes PRC beam motion or not, using temporary oplev to PR2.
I could not measure the coherence between beam motion and PR2 motion, because I couldn't lock half-PRC today.
But I took spectra of PR2 oplev anyway. |
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Tue Feb 12 23:24:17 2013, yuta, Update, Alignment, IFO alignment in prep for in-air PRMI
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[Manasa, Yuta]
Lot's of alignment work, still no AS beam. REFL is clipped by Faraday output aperture...... |
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Wed Feb 13 01:26:08 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Koji was correct.
When you estimate the variance of the population, you have to use unbiased variance (not sample |
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Wed Feb 13 19:09:32 2013, yuta, Summary, General, possible explanations to oval REFL beam
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[Jenne, Manasa, Jamie, Yuta]
The shape of the REFL beam reflected from PRM is oval after the Faraday. |
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Wed Feb 13 19:41:07 2013, yuta, Summary, General, possible explanations to oval REFL beam
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We checked that REFL beam is already oval in the vacuum. We also centered in-air optics, including lens, in the REFL path, but REFL still looks bad.
By using IR card in vacuum, PRM reflected beam looks OK at MMTs and at the back face of the Faraday. But the beam looks bad after the output aperture |
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Thu Feb 14 00:10:12 2013, yuta, Summary, Alignment, REFL is not clipped
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Let's wait for astigmatism calculation.
In either case(clipping or astigmatism), it takes time to fix it. And we don't need to fix it because we can still get LSC signal from REFL.
So why don't we start aligning input TTs and PRMI tomorrow morning. |
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Fri Feb 15 20:07:28 2013, yuta, Update, Alignment, POP path set up but AS55 is broken
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[Manasa, Yuta]
We set up POP camera and POPDC PD, and centered REFL PDs. |
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Fri Feb 15 21:22:29 2013, yuta, Update, Electronics, AS55 replaced with POP55 PD
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I temporarily replaced AS55 PD with PD labeled "POP55(POY55)".
I think POP55 is working because I could lock MI with this PD using AS55_Q_ERR as an error signal. I rotated I/Q phase (C1:LSC-AS55_PHASE_R) to
70 deg by minimizing ASDC during MI lock. |
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Sat Feb 16 17:27:26 2013, yuta, Update, SUS, PRM coil balanced
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PRM coil gains and f2a filters are adjusted for PRMI work.
It seems like UR/LL coil gains were ~10 % larger than others, and f2a filters changed by few %.
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Sat Feb 16 18:32:01 2013, yuta, Summary, RF System, phase tracker: OLTF
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I measured openloop transfer function of the phase tracking loop for the first characterization of phase tracker.
What is phase tracker: |
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Sat Feb 16 19:23:17 2013, yuta, Update, LSC, PR2 flipped PRMI locked
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It is my pleasure to announce that the first lock of PR2 flipped PRMI was succeeded.
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Mon Feb 18 18:28:01 2013, yuta, Bureaucracy, Alignment, we are going to pump down
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We will start preparing for pumping down. Main goal for this is to demonstrate PRFPMI using ALS.
Here are to-dos before we pump down.
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Tue Feb 19 00:21:09 2013, yuta, Update, Electronics, POP path set up but AS55 is broken
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Hmm......
I thought AS55 is broken because it was not responding to the AS beam nor flashlight in DC. What's the DC gain difference between AS55 and POP55
(or REFL55)? |
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Tue Feb 19 02:23:40 2013, yuta, Bureaucracy, General, action items for PRFPMI
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These are things need to be done for demonstrating PRFPMI using ALS.
All of these should be done before March 8!
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Tue Feb 19 08:06:02 2013, yuta, Update, Electronics, POP path set up but AS55 is broken
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I didn't use LED flash light. We learned from the past (elog #7355). I checked that POP55 and
REFL55/165/33/11 are clearly responding to flash flight, but I didn't expect that much difference in DC gain.
I wonder why we could align AS beam to AS55 in Feb 8 (elog #8030), but not in Feb 15 ( |
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Tue Feb 19 19:55:52 2013, yuta, Update, IOO, MC yaw input tuned
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[Jenne, Manasa, Yuta]
Since we levelled IMC stack, we had to center beam spots on MC mirrors again. |
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Wed Feb 20 03:13:10 2013, yuta, Update, Alignment, clipping centering checklist
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I attached clipping/centering checklist for the alignment.
Blue ones are the ones we checked today. Red ones
should be checked tomorrow. Circles indicate centering on the optics, rectangles indicate clipping check, and arrows indicate retro-reflecting |
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Wed Feb 20 10:13:41 2013, yuta, Update, Alignment, PRC flashing brighter than last week
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After in-vac alignment work last night, PRC is flashing brighter than PRMI alignment last week.
My hypothesis is that "we aligned PRM to junk MI fringe last week". Possibly, we used MI fringe caused by AR reflection of ITMs, or MI
fringe reflected from SRM. |
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Wed Feb 20 19:48:16 2013, yuta, Update, Alignment, BS table oplev re-arranged
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[Sendhil, Yuta]
After aligning IFO and putting the access connector on, we also centered IPANG/IPPOS and all oplevs (except SRM). |
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Wed Feb 20 20:15:29 2013, yuta, Update, Alignment, SRM oplev status
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Currently, SRM is misaligned in pitch so that SRM reflected beam hits on the top edge of SR3 (not on the mirror, but on the cage holding the mirror).
We also confirmed that SRM oplev beam is coming out from the chamber unclipped, and centered on QPD when SRM is "aligned". |
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Wed Feb 20 20:58:37 2013, yuta, Update, Alignment, clipping centering checklist
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Blue ones are the ones we checked yesterday.
Green ones are the ones we checked today.
Red ones are the ones we couldn't check. |
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Wed Feb 20 21:56:08 2013, yuta, Update, Alignment, clipping centering checklist
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I'm not sure about the OMC situation at 40m. I think there are no direct beam reflected back into IFO from OMC path. There must be some backscatter,
but we have to open OMC chamber again to put a beam dump.
I don't think we want to put one in OMC path for this pump-down, but we can put a beam dump to dump reflected beam from mis-aligned SRM tomorrow, |